Redetachable, self-adhesive device

ABSTRACT

Redetachable, self-adhesive device having a plate, the sides and/or front side of which have fastening means, if appropriate, and the rear side of which has a strip of an adhesive film which is adhesive on both sides and is adhesively attached in such a way that one end of the adhesive film protrudes beyond the plate as a grip, the adhesive film being of such a kind that the adhesive bond achieved with it can be released again by pulling in the direction of the bonding plane, stretching the strip, characterized in that the rear side of the plate (1) has laterally alongside the adhesively attached adhesive film (5) spacers (3A, 3B), the height of which is less than the thickness of the adhesive film (5).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a redetachable, self-adhesive device which canbe released again from its adhesive bond without leaving any residue bypulling on the adhesive film, arranged on it, in the direction of thebonding plane. In particular, the invention relates to a plate of thistype, on which other things can be fastened if appropriate, or whichitself is designed as a hook or the like if appropriate.

2. Description of Related Art

Such devices, in particular hooks, are known. For instance, DE 42 33 872C2 describes a redetachable, self-adhesive hook which is equipped withan adhesive film which can be adhesively released by pulling and whichis commercially available as "tesa® Power-Strips with Hooks". Aso-called system hook with base plate and attachable decorative hook isalso commercially available as the tesa® Power Strip System Hook.

WO 94/21157 also discloses such a hook, which differs from theabovementioned hook in particular by the use of an adhesive film of thekind which is highly extensible and at the same time does not recoverits original form.

In the practical use of such devices, problems may occur, however, inparticular during later detachment.

What is particularly disadvantageous about the previously known problemsolutions is that the releasing of the adhesive bond has to take placeby pulling the adhesive strips substantially in the bonding plane,errors in use being inevitable for the unexperienced user.

In many cases it has been found that tears are caused by the userexerting considerable force to press the item to be released against theobject to which it is adhesively bonded during the releasing process. Asa result, the force necessary for pulling the adhesive tape out of theadhesive joint is increased to such an extent that the tearingresistance is exceeded, with the unfortunate consequence for the userthat the adhesive tape tears and the adhesive bond can no longer bereleased non-destructively and without leaving any residue.

The object of the invention was to overcome the aforementioneddisadvantages.

SUMMARY OF THE INVENTION

This object is achieved by means of a device such as that characterizedin more detail in the claims. Accordingly, the invention relates to:

A redetachable, self-adhesive device having a plate, the sides and/orfront side of which have fastening means, if appropriate, and the rearside of which has a strip of an adhesive film which is adhesive on bothsides and is adhesively attached in such a way that one end of theadhesive film protrudes beyond the plate as a grip, the adhesive filmbeing of such a kind that the adhesive bond achieved with it can bereleased again by pulling in the direction of the bonding plane,stretching the strip, characterized in that the rear side of the plate(1) has laterally alongside thee adhesively attached adhesive film (5)spacers (3A, 3B), the height of which is less than the thickness of theadhesive film (5).

In particular a device according to claim 1, characterized in that thespacers (3A, 3B) are located on both sides alongside the adhesivelyattached adhesive film (5).

In particular a device according to claim 1, characterized in that thespacers (3A, 3B) are formed as fillets or segments.

In particular a device according to claim 1, characterized in that thespacers (3A, 3B) are arranged on both sides and, on each of these sides,at least in the region of the two ends.

In particular a device according to claim 1, characterized in that it isformed as an injection-moulded part of plastic.

In particular a device according to claim 1, characterized in that theheight of the spacers (3A, 3B) is 35-90% of the thickness of theadhesive film (5), in particular is 0.3-0.6 mm in the case of athickness of the adhesive film (5) of 0.65 mm.

In particular a device according to claim 1, characterized in that theadhesive film (5), with or without an intermediate substrate, iselastically or plastically extensible.

In particular a device according to claim 1, characterized in that theadhesion of the adhesive film (5) is less than the cohesion, theadhesiveness is dissipated to a great extent when the film is extended,and the ratio of pulling-off force to tearing load is at least 1:1.5,the adhesive film being of the kind which is based on thermoplasticrubber and tackifying resins, with high elasticity and low plasticity.

In particular a device according to claim 1, characterized in that therear side of the adhesive film (5) is covered with a release laminate,such as a siliconized release paper or a release film.

In particular a device according to claim 1, characterized in that atthe sides of the plate (1) there are engaging devices (4) into which acorresponding hook or the like can be engaged.

DETAILED DESCRIPTION OF THE INVENTION

The height of the spacers is advantageously chosen such that it is lessthan the thickness of the (unstretched) adhesive film, so that asatisfactory adhesive bond with the adherent surface is possible. Theextension of the adhesive film occurring during the detachment operationcauses the said film to be reduced correspondingly in width andthickness. If the thickness of the adhesive film reached duringdetachment is less than the height of the spacers, detachment of theadhesive film without tearing is even possible if high contact pressuresoccur at the same time vertically to the adhesive bond, which wouldotherwise have lead to tearing of the adhesive tape.

According to the invention, suitable in particular as adhesive films arethose corresponding to DE 33 31 016, DE 42 22 849, DE 42 33 872, WO92/11333 and WO 94/21157.

For instance, DE 33 31 016 A1 describes an adhesive film forre-releasable adhesive bonds which allows an adhesive bond establishedtherewith to be released by pulling on the adhesive film in thedirection of the bonding plane. With such adhesive films, high adhesiveforces and shear strengths can be achieved and adhesive bonds can bereleased again without further aids, in a way comparable to the openingof a preserving jar, similar to the way in which there the rubber sealis pulled by the grip out of the seal joint.

DE 42 22 849 C1 describes such an adhesive film with a UV-impermeablegrip.

WO 92/11333 also describes, inter alia, adhesive films for correspondingapplications, the adhesive films used having a low elasticity with atthe same time high extension.

Double-sided self-adhesive tapes with a foam intermediate substrate, forexample of polyethylene foam, can also be used according to theinvention.

In general, for production, processing and handling of the particularlypreferred adhesive films, reference is made to DE 33 31 016, DE 42 22849 and WO 92/11333.

Suitable as the material for the plate or moulding, in particular forbase plates, are:

Plastic, metal, wood (coated, for example painted, and uncoated),ceramic and the like.

Devices according to the invention serve for receiving one side of theadhesive film, the other side of which is adhesively bonded onto theselected underlying surface. A wide variety of adapters, including hookbodies, can be placed onto the device or plate. To produce a highbonding strength, the surface of the plate on the side to which theadhesive film is applied consists in particular of a material which hasan adhesion with respect to the adhesive film which is adequate for therespective application. When using contact adhesives based on styreneblock copolymers or acrylate copolymers, advantageously used in thiscase are, inter alia, polystyrene, impact-modified polystyrenes, PMMA,aromatic polyesters, polycarbonate or polyamide.

To accomplish a pulling-off behaviour without tearing, even under theeffect of high forces acting perpendicularly with respect to the bondingplane (for example caused by high contact pressure when releasing theadhesive bond), the plate is equipped with spacers (for examplefillets), as still to be described in detail, on the side which bearsthe adhesive film.

Spacers may be provided on both sides alongside the adhesive film overthe entire length of the base plate, or else only in certain subregionsthereof. Specific formations, right-angled fillet-like, rounded-offfillet-like, punctiform etc., are possible.

Tests with different redetachable adhesive films show that, depending onthe type and structure of the adhesive films used, typical strippingextensions lie between 100% and 800%. In practice, it is found that, inthe case of substantially rubber-elastic adhesive films, the height ofthe spacers should be at least about 0.05 mm, preferably 0.10 mm, higherthan the thickness of the stretched adhesive films during the detachmentprocess. For a reliable adhesive bond, on the other hand, the spacerheight should be kept about 0.05 mm, preferably 0.1 mm, particularlypreferably 0.15 mm, less than the thickness of the adhesive films in thenon-stretched state. The values specified relate to planar, solidadherent surfaces. In the case of rough and/or slightly deformableadherent surfaces, values higher than those quoted may be advisable bothfor a satisfactory bonding process (adequate contact pressure) and forsatisfactory redetachment.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is to be explained in more detail below with reference toexemplary embodiments, without however wishing to restrict itunnecessarily. In the drawing:

FIG. 1 shows an obliquely lateral view of a device according to theinvention,

FIG. 2 shows a side view according to FIG. 1, with an adhesivelyattached adhesive film strip,

FIG. 3 shows an end view according to FIG. 1,

FIG. 4 shows a side view according to FIG. 2, the device beingadhesively attached by its adhesive film strip to an object, and

FIG. 5 shows an end view according to FIG. 4.

To be specific, FIG. 1 shows a plate 1 with a rear side 2, which servesfor receiving a strip of double-sided adhesive film and has spacers 3A,3B in the form of fillets to the sides of the adhesive film to beadhesively attached. On its sides, the plate 1 also has engaging devices4, into which a corresponding device can engage, for instance a platewith a hook or some other fastening device, as is standard andcommercially available.

FIG. 2 shows how a strip 5 of an adhesive film is adhesively attached tothe plate 1, it being indicated by the dotted line 6 how the spacers 3Aand 3B partially enclose the strip 5 to the sides, while one end of theadhesive film protrudes beyond the plate 1 as a grip 7. In FIG. 3, as anend view of the plate 1, the latter is represented with the spacers 3A,3B and also with the engaging devices 4.

FIG. 4 shows in a lateral view how such a device is adhesively attachedto an object 8, for instance a wall, a door or a cupboard, with plate 1,strip 5 of an adhesive film, the grip 7 protruding beyond one end of theplate 1, the grip 7 being made non-adhesive by thin films 9A, 9B. InFIG. 5, this arrangement is represented in an end view, with plate 1,strip 5 of an adhesive strip, and also spacers 3A, 3B which laterallyenclose the strip 5 and extend to about half the thickness of the strip5.

EXAMPLE

For a single-layer adhesive film of the following formulation:

50 parts of Foralyn 110 (Hercules), 50 parts of Vector 4211 (ExxonChemical), 0.5 parts of Irganox 1010 (Ciba) of a thickness of 650 μm, amaximum tensile force of 52 N/cm, corresponding to 8.0 MPa, and anultimate elongation of 1300% are determined.

Rectangular pieces of the adhesive film measuring 20 mm×50 mm areadhesively bonded centrally to base plates consisting of steel of thedimensions 3 mm×40 mm×22 mm (height×length×width) in such a way that thebase plates are covered on one side over their entire length by theadhesive film and a 10 mm long strip of adhesive film protrudes beyondone of the short sides of the base plate, which can be used as a gripfor later detachment. The base plates are provided on both longitudinaledges on the side to which the adhesive films are applied with spacers0.5 mm wide and of different heights. The base plates provided withadhesive films are adhesively bonded onto a planar underlying surface ofResopal. For this purpose, the base plates provided with the adhesivefilms are applied flatly to the underlying Resopal surface and pressedonto it with 500 N for 5 seconds. In a second operation, for detachingthe adhesive films, the test pieces fixed in this way are subjected to aforce of likewise 500 N, acting vertically onto the bonding plane, andthen the adhesive film strip is pulled out of the adhesive joint at anangle of <10° with respect to the bonding plane. For comparison, thetests are carried out without any force acting vertically on the bondingplane. The stripping rate in all the tests is about 1000 mm/min. Thefollowing results are obtained.

    ______________________________________                   Vertical pressing                                Without    Height of the spacers                   force 500 N  vertical force    ______________________________________    No spacer      Strip tears  Can be detached                                without tearing    0.3            Can be detached                                Can be detached                   without tearing                                without tearing    Stripping force*                   10//14 N/cm    0.4 mm         Can be detached                                Can be detached                   without tearing                                without tearing    Stripping force*                   9//15 N/cm    0.5 mm         Can be detached                                Can be detached                   without tearing                                without tearing    Stripping force*                   9//10 N/cm    0.6 mm         Can be detached                                Can be detached                   without tearing                                without tearing    Stripping force*                   9//10 N/cm    0.7 mm         No adhesive  No adhesive                   bonding possible                                bonding possible    ______________________________________     *Mean value//maximum value (the maximum value is reached at the end of th     stripping operation).

Under the chosen test conditions, only base plates provided with spacerscan be detached again without tearing under the effect of high verticalforces acting on the base plate.

We claim:
 1. A redetachable, self-adhesive device comprising:a) a platehaving a front, a rear and four sides; b) a double-sided adhesive stripof film adhered to the rear of said plate through an adhesive bond insuch a way that one end of said adhesive film strip protrudes from saidplate as a grip; and c) a plurality of fasteners protruding from thesides of said plate for fastening said plate to another device;whereinthe adhesive bond between said adhesive film strip and said platecan be released by pulling and stretching the adhesive film strip; andthe rear of said plate (1) has laterally alongside the adhered adhesivefilm strip (5) spacers (3A, 3B having a height), the height of which isless than the thickness of the adhesive film strip (5).
 2. Deviceaccording to claim 1, wherein the spacers (3A, 3B) are located on bothsides alongside the adhesively attached adhesive film (5).
 3. Deviceaccording to claim 1, wherein the spacers (3A, 3B) are formed as filletsor segments.
 4. Device according to claim 1, wherein the spacers (3A,3B) are arranged on both sides and, on each of these sides, at least inthe region of the two ends.
 5. Device according to claim 1, which isformed as an injection-moulded part of plastic.
 6. Device according toclaim 1, wherein the height of the spacers (3A, 3B) is 35-90% of thethickness of the adhesive film strip (5).
 7. Device according to claim1, wherein the adhesive film (5), with or without an intermediatesubstrate, is elastically or plastically extensible.
 8. Device accordingto claim 1, wherein the adhesion of the adhesive film strip (5) is lessthan the cohesion, the adhesion is to a great extent dissipated when thefilm is extended, and the ratio of pulling-off force to tearing load isat least 1:1.5, the adhesive film strip being of the kind which is basedon thermoplastic rubber and tackifying resins.
 9. Device according toclaim 1, wherein the rear side of the adhesive film strip (5) is coveredwith a release laminate.
 10. Device according to claim 1, wherein aspacer is arranged at one of the end faces on the rear side of the plate(1) alongside the adhesively attached adhesive film (5).
 11. Deviceaccording to claim 6, wherein the height of the spacers (3A, 3B) is0.3-0.6 mm and the thickness of the adhesive film strip (5) is 0.65 mm.12. Device according to claim 9, wherein the release laminate is asiliconized release paper or a release film.
 13. A method of forming atemporary bond between a substrate and a device according to any one ofclaims 2-9, 10, 11 and 12, which bond can be released easily and withoutresidue, said method comprising adhering said device to said substrateby means an adhesive bond formed between said substrate and saidadhesive film strip, and thereafter releasing said device from saidsubstrate by pulling on the grip of said adhesive film strip at an angleapproximately perpendicular to the plane of the bond formed between saidsubstrate and said adhesive film strip.